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The Weather portal

Thunderstorm near Garajau, Madeira

Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the lowest level of the atmosphere, the troposphere, just below the stratosphere. Weather refers to day-to-day temperature and precipitation activity, whereas climate is the term for the averaging of atmospheric conditions over longer periods of time. When used without qualification, "weather" is generally understood to mean the weather of Earth.

Weather is driven by air pressure, temperature and moisture differences between one place and another. These differences can occur due to the sun's angle at any particular spot, which varies with latitude. The strong temperature contrast between polar and tropical air gives rise to the largest scale atmospheric circulations: the Hadley Cell, the Ferrel Cell, the Polar Cell, and the jet stream. Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow. Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. On Earth's surface, temperatures usually range ±40 °C (−40 °F to 100 °F) annually. Over thousands of years, changes in Earth's orbit can affect the amount and distribution of solar energy received by the Earth, thus influencing long-term climate and global climate change.

Surface temperature differences in turn cause pressure differences. Higher altitudes are cooler than lower altitudes, as most atmospheric heating is due to contact with the Earth's surface while radiative losses to space are mostly constant. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. The Earth's weather system is a chaotic system; as a result, small changes to one part of the system can grow to have large effects on the system as a whole. Human attempts to control the weather have occurred throughout history, and there is evidence that human activities such as agriculture and industry have modified weather patterns.

Studying how the weather works on other planets has been helpful in understanding how weather works on Earth. A famous landmark in the Solar System, Jupiter's Great Red Spot, is an anticyclonic storm known to have existed for at least 300 years. However, weather is not limited to planetary bodies. A star's corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from the Sun is known as the solar wind.

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A blizzard has swept the snow on these trees on The Brocken (Harz, Germany) into weird shapes.

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Cleveland blizzard 1913, poles down.png
The Great Lakes Storm of 1913 was a blizzard which produced hurricane-force winds that devastated the Great Lakes basin in the United States Midwest and the Canadian province of Ontario from November 7, 1913, to November 10, 1913.

The deadliest and most destructive natural disaster to ever hit the lakes, the storm killed over 250 people, destroyed 19 ships, and stranded 19 others. It produced 6-foot drifts of snow in the surrounding land areas, snapped power poles, and paralyzed many areas for days, especially the area around Cleveland, Ohio.

The financial loss in water-bound vessels alone was nearly $5 million, or about $100 million in present-day adjusted dollars. The large loss of cargo, including coal, iron ore, and grain, meant short-term rising prices for consumer products throughout North America.

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Did you know...

...that the Oklahoma Mesonet is a network of 121 weather instruments across US state of Oklahoma, providing surface weather observations across the state every five minutes?

...that a SIGMET is an advisory issued for airline crews regarding weather that may impact the safety of the aircraft, including atmospheric convection, icing conditions, or even dust storms?

...that the Antarctic Circumpolar Wave is thought by some scientists to be a very slow-moving wave in the atmosphere and ocean of the far southern hemisphere that circles the globe once every 8 years?

...that the Papagayo Jet is a strong wind that often blows across the Gulf of Papagayo west of Central America, sometimes reaching speeds as high as 30 meters per second (110 km/h; 67 mph)?

...that atmospheric optics is the study of different optical phenomena in the atmosphere, including sunsets, rainbows, and sun dogs?

...that the GME was a numerical weather prediction model run by Deutscher Wetterdienst, the German national meteorological service?

Recent and ongoing weather

This week in weather history...

August 22

1997: Tropical Storm Zita made landfall on the Leizhou Peninsula of China, killing 7 people due to flooding and landslides.

August 23

1853: The World Meteorological Organization, originally the International Meteorological Organization, was formed.

August 24

1893: A hurricane struck New York City, causing major damage, including the complete destruction of Hog Island.

August 25

1635: A major hurricane struck southeastern New England, killing more than 46 people.

August 26

2017: Hurricane Harvey made landfall near Rockport, Texas before stalling for several days and producing up to 60 inches (150 cm) of rain in Southeast Texas. This was the most rainfall on record in the United States from a tropical cyclone.

August 27

1989: Hurricane Kiko (1989) struck the southern tip of Baja California as a category 3 hurricane, but caused no deaths.

August 28

1983: Hurricane Barry made landfall about 35 miles (56 km) south of the Texas border, in the Mexican state of Tamaulipas. Hundreds of homes were destroyed, but no one was killed.

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Portrait of John Dalton FRS

John Dalton FRS (6 September 1766 – 27 July 1844) was an English chemist, meteorologist and physicist. He is best known for his research into colour blindness and his pioneering work in the development of modern atomic theory, which came out of his initial interest in meteorology and atmospheric chemistry. He aided in the rediscovery of George Hadley's theory of atmospheric circulation: the Hadley cell, and published a book, Meteorological Observations and Essays, where he speculated on the nature of the atmosphere, its motion, and its chemistry.

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WikiProject Meteorology is a collaborative effort by dozens of Wikipedians to improve the quality of meteorology- and weather-related articles. If you would like to help, visit the project talk page, and see what needs doing.

WikiProject Severe weather is a similar project specific to articles about severe weather. Their talk page is located here.

WikiProject Tropical cyclones is a daughter project of WikiProject meteorology. The dozens of semi-active members and several full-time members focus on improving Wikipdia's coverage of tropical cyclones.

WikiProject Non-tropical storms is a collaborative project to improve articles related to winter storms, wind storms, and extratropical weather.

Wikipedia is a fully collaborative effort by volunteers. So if you see something you think you can improve, be bold and get to editing! We appreciate any help you can provide!

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